Aerodynamic lifting device and method of lifting



United States Patent [72] Inventor Norman Bryan McCreary 45 Lakeshore Drive, Little Rock, Arkansas [21] Appl. No. 471,489 [22] Filed June 1, 1965 Continuation of Ser. No. 72,348, Now. 29. 1960,v1hichis a continuation-in-part of Ser. No. 20,799, Apr. 5. 1960, abandoned. which is a continuation-in-part olSer. No. 14,782, Mar. 14. 1960, abandoned. [45] Patented Oct. 6,1970

[54] AERODYNAMIC LIFTING DEVICE AND METHOD OF LIFTING 28 Claims, 57 Drawing Figs.

[52] U.S.Cl 180/117, 180/118,180/119,180/12l,180/124,180/127 [51] Int. Cl 860v 1/06, B60v l/14, 860v 1/16 {50] Field ofSearch 180/71FS1.

[56] References Cited UNITED STATES PATENTS 936,395 10/1909 Worthington 2,743,787 5/1956 Seek 3,055,446 9/1962 Vaughen 180/7 3,066,753 12/1962 Hurley 6161.; 180/? 9 .71 /1963 Jay et a1 180/7 3,177,959 /1965 Gaska 180/7 3,182,739 5/1965 Cockerell 180/7 OTHER REFERENCES Publication: Aviation Week" July 6,1959 Publication: The New York Times" Oct. 1, 1959 Publication: Science And Mechanics" June 1960 Primary Examiner-A. Harry Levy Attorney-Cushman, Darby and Cushman ABSTRACT: A ground proximity fluid cushion supporting device comprising. a platform. a flexible diaphragm underlying said platform shaped to provide a perimetrical depending convolution, the periphery of said diaphragm being hermetically attached to said platform and the central portion thereof being restrained in a fixed position beneath said platform above the lower most extremity of said convolution thereby forming a plenum cavity between said diaphragm and the ground and an annular cavity between said diaphragm and said platform, means formed inboard of said convolution providing direct communication between said annular cavity and said plenum cavity, and means for introducing fluid under pressure directly into one ofsaid cavities.

Patented Oct. 6, 1970 Sheet INVENTOR NORMAN BRYAN MCCREARY Patented Oct. 6, 1970 3,532,179

Sheet 2 of 15 INVENTOR NORMAN BRYAN MCCREARY F I 3 7 309A I Patented Oct. 6, 1970 Sheet WALK IfTdF/VJKS Patented Oct. 6, 1-970 Sheet C mm mm. m

VI R A E R w WM MN m MR IB N A M R 0 N Sheet 7 of 15 FIGJ9 Patented Oct. 6, 1970 3,532,179

Sheet 8 0t 15 328 NORMAN BRY'R'J a gEARY FIG.22

Patented Oct. 6, 1970 79 sheet 9 of 15 F'IG.25

FIG. 26

52 mam;

- INVENTOR NORMAN BRYAN McCREARY FIG.28

Patented Oct. 6, 1970 Sheet /0 of 15 ENGINE FIG.29

EMS/ML,

FlG.32 568 FIG. 33 568 INVENTOR NORMAN BRYAN MCCREARY Patented Oct. 6, 1970 I/ or 15 Sheet FIG. 36

III]

652 608 F I G 675 674 INVENTOR NORMAN BRYAN M -CRE ARY Patented 0a. 6, 1970 3,532,119

Sheet /3 of 15 INVENTOR x NORMAN BRYAN M- GREARY Patented Oct. 6, W70

Sheet 1 of 15 FEG. 53

. IOIO INVENTOR NORMAN BRYAN M'QGREARY AERODYNAMIC LIF TING DEVICE AND METHOD OF LIFTING This application is a continuation of my copending application U.S. Ser. No. 72,348, filed Nov. 29, 1960 and now abandoned, and is a continuation-in-part of my copending application U.S. Ser. No. 20,799, filed Apr. 5, 1960 and now abandoned, which last mentioned application in turn is a continuation-in-part of my copending application U.S. Ser. No. 14,782 filed Mar. 14, 1960 and now abandoned.

This invention relates to an aerodynamic lifting device and method of lifting which may be used in a plurality of ways, for example, as a toy for amusement, a toy for educational purposes, an amusement device for use in amusement parks and the like, an educational device for use in lectures on aerodynamics and the like, a transportation device on which a load may be placed with the device being pulled, a transportation device which may self propelled, a transportation device which may be used amphibiously over land and water, and as a device having a relatively rigid support member from which a relatively flexible curtain is supported, which curtain aids in enclosing an air cushion for lifting the relatively rigid support member a substantial distance above the ground surface (the words ground surface" or ground" being used in a broad sense to include both land and water and the like). These uses are by way of example only, and are intended to show only some of the many uses to which the invention may be applied.

Accordingly, several forms of the invention are illustrated in the drawings diagrammatically in a manner to enable those skilled in the art to make aerodynamic devices according to this invention.

Some of the forms illustrated are shown without selfpropelling or guiding means and may be used stationarily or may be pulled or pushed along, as desired. These same forms, and other forms illustrated, may be provided with selfpropelling and/or guiding means. These self-propelling and/or guiding means may be in the forms of weights, jets, valves, fans, and the like. All of these self-propelling and/or guiding means may all be placed on a single device and may be used simultaneously, sequentially, or singly. They may also be used together to modify each other and may be used sequentially where various conditions of travel are encountered. They may be used, for example, at a lecture, where the efficacy and relationship of each particular control device may be illustrated as the lecture proceeds. These various selfpropelling means may be used together, each to modify each other, under certain conditions of propulsion or travel. These self-propelling and/or guiding means may all be placed on a toy to enhance the attractiveness and interest therein and to supply a variety of uses for the toy, or any one or more of these means may be used in a less number than the particular illustration, as desired. Any or all of these self-propelling and/or guiding means may be used in all embodiments where they are applicable.

The self-propelling and/or guiding means may be manually set, for example, on a toy or lecture educational device to produce the propulsion and guidance desired. When manually settable they may be provided with sufficient frictional resistance to displacement to remain in the manually set position. These propulsion and/or guidance means may be also ac tuated to the desired condition or position by actuating means in which the manipulator, pedal, handle, or guiding wheel, and the like, may be relatively distant from the self-propelled and/or guiding means.

At the present development of industry, the art of actuating a device, such as ajet, vane, valve, blower, and the like, from a distant control member such as by a lever, switch, key, wheel, and the like, has attained the status of a well-developed industry. Such industry can now provide controllers of this type, which easily and efficiently produce such motions as the turning ofa vane, the moving of a valve, the turning of the effective direction of any device, such as a blower or electric fan or the like, the moving of a weight, and other such means. This industry can provide means to move these devices proportionately to the movement of the controlling switch, lever, wheel, or the like. For example, small motors are available which are controlled by suitable switches having suitable levers and the like. The motors are reversible, if desired, and are provided with actuating levers, gears, such as worm gears, and other well-known movements to produce the desired motion of the desired device. For example, windows on automobiles are now moved upward and downward by the mere corresponding motion of an upward or downward movement of a small lever on a switch, or the like. The movement of the window has been produced hydraulically, as well as by small motors. Varies on airplanes and many other devices on airplanes are controlled by proportionally movable controllers at the pilot's cabin. Small motors, and the gearing, and slip clutches, etc., actuated thereby, are made and sold by many manufacturers, such as General Motors Corporation of Detroit, Michigan, Globe Industries, Inc., of Dayton, Ohio, and many others. These and other manufacturers produce actuators" capable of proportionally actuating a device from a relatively long distance proportionally to the movement of the control member adjacent the user and particularly controllers for automobile windows and all of the necessarily movable parts on an airplane and the like. The very small motors which they provide, by way of example, may be energized from a small battery which may be chargeable during operation of the vehicle or the like or during its idle periods, as desired. Accordingly, applicant has illustrated only the novel correlation of the propulsion and/or guiding members, in many instances, since the actuator system has now attained a well-known and conventional status of its own and hence can be provided or purchased, need not be specifically illustrated in detail.

However, merely by way of example, some of such actuator systems of distant control have been illustrated to show typical systems for use in controlling some of the vanes, weights, and the like, which are shown herein. It is to be understood that such actuator systems, and similar systems, both mechanical and/or electrical, may be used to actuate any of the controls herein disclosed. Additionally, it is understood that any of the controls illustrated on any one embodiment may be used in other embodiments, as desired, and every conceivable permutation is not specifically shown, in the interest of avoiding superfluous illustrations. 7

Where the aerodynamic lifting device is intended for use in transporting a load, such as a passenger load and the like, over water, suitable pontoons may be incorporated in any of the embodiments disclosed. Such pontoons are illustrated and described hereinafter as applied to a typical embodiment, but are applicable to all embodiments. Such application of pontoonsisnot repeated to avoid superfluous illustrations.

-This invention relates to a vehicle, craft, or glider which lifts itself from a ground surface by a cushion of air which is maintained at superatmospheric air pressure. The air cushion produces a lifting action as it presses upward against the under surfaces of the supporting member to overcome the downward pressure of atmospheric air on the upper surfaces of such supporting member. The air cushion is surrounded by a substantially air impervious cylindraceous or columnar side wall construction which prevents any substantial uncontrolled escape of the superatmospheric air of the air cushion except at a relatively narrow space under the lower edge of the columnar side wall construction. Only a small amount of power is required to operate air moving means which blows air from the surrounding atmosphere into the air cushion to replace the air which escapes under said lower edge ,of the columnar construction.

The narrow space between the lower edge of the columnar construction and the ground" surface permits the craft to move or be moved sidewise over the ground surface. A relatively high, thin, flexible, air impervious curtain forms a substantial portion of the lower part of the columnar construction. Such curtain can extend upwardly from the lower edge of the columnar construction for a relatively great distance to permit such curtain to flex and passover relatively large obstructions, such as large stories, etc., without harm to the relatively rigid upper supporting member. The lower space within the curtain is unobstructed by any rigid parts of the craft during normal operation, so the craft may pass over such large stones, etc., without damaging or jarring impact. In this manner the craft may move over a relatively rough ground surface and still maintain a relatively narrow escape space at the bottom of the curtain.

The flexible curtain also permits the craft to be tilted for control purposes, and/or to compensate for hills or slopes to maintain the supporting member substantially level.

The vehicle, craft or glider may be used to transport any desired loads, both animate or inanimate, over the surfaces of land, marshes, or open water, and such surfaces are intended to come under the convenient description of ground" surface.

Such vehicles, crafts, or gliders may be used for amusement purposes in amusement parks, as a toy at home, or elsewhere, or they may be used for practical purposes such as for the transportation of persons or things over relatively long distances over land or water. They may be used singly or in joint formation for various purposes. They may be used amphibiously and interchangeably over land, marsh, or water surfaces.

In some embodiments herein disclosed, all of the parts of the craft are distributed to produce a substantially equally balanced weight condition throughout the craft. The weights of the parts normally are distributed about a vertical axis to provide a balanced condition without tilting action.

A relatively thin flexible curtain encloses at least a part of the air cushion in a manner to prevent undue loss of the air within the cushion. This thin flexible curtain automatically maintains itself in upright position notwithstanding that its material is practically non-self-supporting edgewise. The curtain is so shaped that it easily glides over relatively high obstructing objects and relatively rough ground" surface in a surprising manner.

The thin and flexible curtain maintains the solid or unyielding parts of the supporting member at a relatively great height above the ground surface so that such solid or unyielding parts pass over relatively high objects without impact, while the thin and flexible curtain yields and glides over such high objects without jarring effects on the solid or unyielding parts ofthe supporting member.

To this end, a supporting member, during normal operation, is supported by an air cushion at superatmospheric pressure. The lower part, or more, of the air cushion is surrounded and is retained by a thin, flexible, hollow, columnar curtain which has its lower edge slightly spaced from a ground" surface, during normal operation, to permit restrained escape of air from said cushion between the lower edge of the curtain and the ground" surface. Air moving means withdraws air from the surrounding atmosphere and discharges said air at superatmospheric pressure into said air cushion to maintain the air in the cushion at superatmospheric pressure.

Such superatmospheric pressure may be as low as a fraction of'an ounce per square inch above the pressure of the surroundingatmosphere adjacent the craft. Such low superatmospheric pressure may be maintained on all of the embodiments herein disclosed. This low differential ofa fraction of an ounce per square inch permits the curtain to yield in a surprising manner when passing over obstructions without damage to the curtain or to the remainder of the craft. However, higher superatmospheric air pressures may be used when desired.

The construction is such that it automatically raises itself and a load from the ground" surface when the blowing means starts. it correctly shapes and forms the curtain by automatic reaction, and automatically lowers itself when the blowing means stops.

Preferably the curtain is supported at its upper edge by the supporting member and has an outer, substantially vertical wall and an inner wall which extends upwardly and inwardly from the lower edge of the outer wall into the air cushion. The

air of the main part of the air cushion flows freely in and out of the space between the inner and outer walls automatically to fill such space with air at superatmospheric pressure and to cause the air cushion to raise the structure from the ground".

The curtain provides a large vertical clearance above relatively high obstacles over which the structure may glide without perceptible impact, since the curtain is very flexible and adjusts itself for yielding movement over such high obstacles.

The slanting construction of the inner wall of the curtain readily permits it to pass over such objects both while the objects enter into and leave the space inside the curtain. The lower part of the air cushion is free of internal members with which such objects could otherwise collide. This permits the structure to pass over rough ground surface and high obstructions without damage or jarring effects on the structure.

The construction of the curtain is such that it automatically restores itself to normal operating condition if relatively high objects are encountered, or if the structure is temporarily tilted.

In some embodiments of this invention, the structure may be given a horizontal or sidewise movement by tilting the structure. The relatively high curtain height makes it possible to provide a sharp tilt, such as 20 30 from horizontal position, which allows forward motion, sidewise motion, backward motion, or braking action, even on steep hills and the like.

The words ground surface as generally used herein are intended to include the surface ofa body of water, floors, or any other surface over which the structure of this invention is to glide or hover.

Wheels or skids may be provided which can be lowered, if desired, either by deflation of the air cushion, or by proper linkage while the air cushion is maintained.

The structure of this invention permits a gliding action over water, and the curtain structure readily adjusts itself to wave motions and the like.

The structure may be used for interchangeable use over land and water, and it may readily pass from one to the other, and vice versa.

If desired, a plurality of concentric or otherwise nested curtains of this invention may be used together under a single supporting member, ramp, or platform, to produce a gradual restraining air flow out from the central part of the structure, under the plurality of concentric or otherwise nested curtains.

The invention may be embodied in all sizes. For example, it may be made with supporting platforms of from a few inches to many feet in lateral dimensions, as desired.

This invention is applicable also for general transportation or supporting action. It may be applied to transportation over land and/or water by many types of vehicles, such as passenger. freight vehicles ofthe automotive and/or trailer type.

In some of the embodiments of this invention, the aerodynamic lifting device may include a lifting platform having a relatively rigid supporting member with a peripheral orbital support for the curtain. An orbital, flexible, channelshaped, sheet curtain may be provided with an outer edge secured to the peripheral orbital support and with an inner edge secured to a support inside of the peripheral orbital support and under said rigid upper supporting member. The curtain may have an intermediate low periphery between said inner and outer edges and there may be a peripheral air space between said curtain edges, and there may be a core air space inside of said inner edge. A superatmospheric pressure air supply means is provided to introduce superatmospheric air into said spaces to form an air cushion below said supporting member to lift said supporting member with said intermediate low periphery of said curtain spaced slightly above a ground surface which is under said lifting device.

Some of the features of this invention are applicable to a lifting device in which the relative vertical distance or extent of the curtain need not be as high as in other instances. The relative height of the flexible curtain may be chosen to provide the desired lift or clearance of the supporting member above the ground surface.

The orbital, flexible, channel-shaped, sheet curtain may be V-shaped, U-shaped, or of other channel shape construction, depending upon the height of the curtain, the strength of the flexible material, and other factors, as desired.

The peripheral air space and the core air space may have superatmospheric air at substantially equal pressures. If desired, such air spaces may be interconnected or separated. The airsupply means for such air spaces may be effective to start and stop substantially simultaneously the air supply both of said air spaces.

Also, if desired, a plurality of curtains, side by side, may be placed under a single supporting member, ramp, or platform and the like, to support the same in a similar manner.

For example, in certain embodiments a plurality of such flexible curtains may be secured to and depend from the supporting member in such a manner that the supporting member does not tend to tilt when the load upon it is off center. In such embodiments, the curtains may be of substantially equal size, if desired, and tend to resist any tilting action. In such embodiments, if it is desired to provide self-propelling and guiding means, such means may take the form of jets, and the like, which may be supplied with superatmospheric air, either from the air supply to the curtains, or from a separate air supply or separate air blower or blowers, which may be used solely for the jet action, as desired.

Accordingly, it is among the many objects of this invention to provide vehicle, craft, or glider which embodies one or more of the novel features and/or methods herein disclosed. Other objects are apparent from this description and/or the accompanying drawings, in which:

FIG. 1 is a plan view, with parts broken away, of one embodiment of this invention.

FIG. 2 is a cross section along the line 2-2 of FIG. 1.

FIG. 3 is a side elevation of one of the skids, with many parts omitted, except the top panel member.

FIG. 4 is a top plan view of the embodiment of FIG. 1, showing controls which may be added thereto.

FIG. 4A is a perspective view of a modified form of the invention shown in FIG. 1.

FIG. 5 is the vertical cross section of a representative em bodiment to which certain additions have been applied.

FIG. 6 is a cross section showing the formation of a curtain according to the present invention from a band of material.

FIG. 7 is a top plan view of another embodiment of this invention.

FIG. 8 is an elevational view of the embodiment of the present invention shown in FIG. 7.

FIG. 9 is the cross section along the line 99 of FIG. 7.

FIG. 10 is the diagrammatic representation of any of the embodiments of this invention passing over a relatively high object.

FIG. 11 is a plan view of another embodiment of this inven mm.

FIG. 12 is a cross section along the line 12-12 of FIG. 11.

FIG. 13 is an elevational view of a portion ofthe embodiment of the present invention shown in FIGS. 11 and 12. as viewed from the line I3- I3ofFIG. 12.

FIG. I4 is a side elevational view ofthe embodiment ofthe present invention shown in FIGS. 11 to 13, showing the front end tilted down and the rear end elevated, to produce a forward motion.

FIG. I5 is a front elevational view showing the embodiment of FIGS. II to 13, with one side tilted down and the other side tilted up to produce a sidewise motion.

FIG. 16 is a diagrammatic illustration of a control for the rudder vane construction of FIGS. 11 to 13.

FIG. 17 is a diagrammatic illustration of the controls for the elevator-depressor vanes of FIGS. 11 to I3.

FIG. 18 is a diagrammatic illustration of the controls for the aileron vanes of the embodiment of the present invention shown in FIGS. 11 to 13.

FIG. I9 is a plan view of an embodiment of the present invention similar to that disclosed in FIGS. 11 to 18 but showing, diagrammatically, a weight construction which may be moved in any direction to tilt the embodiment in any direction desired.

FIG. 20 is a diagrammatic illustration of one method of moving the weight constructions of FIG. 19 in any desired direction.

FIG. 21 is a plan view of another embodiment of this invention.

FIG. 22 is a cross section along the line 22-22 of FIG. 21.

FIG. 23 is an end elevational view of the embodiment of the invention shown in FIGS. 21 and 22.

FIG. 24 is a side elevational view showing the embodiment of FIGS. 21 to 23, with the curtain collapsed and the embodiment resting on skids or the like.

FIG. 25 is a diagrammatic representation of another embodiment of the present invention somewhat similar to FIG. 12.

FIG. 26 is a diagrammatic view of still another embodiment of the present invention including a plurality of units.

FIG. 27 is a diagramatic view in vertical section of another embodiment of the present invention.

FIG. 27A is a fragmentary view in vertical cross section of a modified curtain construction according to the present invention.

FIG. 28 is a fragmentary elevational view partly in section showing an additional feature for the embodiment of FIG. 12.

FIG. 29 is a vertical view, partly in section, of another embodiment of the present invention.

FIG. 30 is a vertical view of still another embodiment.

FIG. 30A is a side elevation view of a modification of the embodiment of the invention shown in FIG. 30.

FIG. 31 is a plan view ofa modification of the embodiment ofthe invention shown in FIG. 30.

FIG. 32 is a fragmentary diagrammatic vertical view of an embodiment of the present invention having a single wall curtam.

FIG. 33 is a view similar to FIG. 32 showing still another embodiment of the present invention utilizing a single wall curtain.

FIG. 34 is a plan view of another embodiment of the present invention.

FIG. 35 is a vertical cross section along line 35-35 of FIG. 34.

FIG. 36 is a horizontal cross section along line 36-36 of FIG. 35.

FIG. 37 is a diagrammatic horizontal cross section on reduced scale showing another embodiment of the present invention somewhat similar to that shown in FIG. 36.

FIG. 38 is a diagrammatic vertical cross section along line 38-38 of FIG. 37.

FIG. 39 is a view somewhat similar to FIG. 37 but showing a different embodiment of the present invention.

FIG. 40 is a diagrammatic vertical cross section along line i 40-40 of FIG. 39.

FIG. 41 is a view somewhat similar to FIGS. 37 and 39, but showing a different embodiment of the present invention.

FIG. 42 is a diagrammatic vertical cross section along line 42-42 ofFIG.4l.

FIG. 43 is a diagrammatic top plan view of another embodiment of the present invention.

FIG. 44 is diagrammatic top plan view of another embodiment of the present invention.

FIG. 45 is a diagrammatic vertical cross section showing an independent air supply for directional propelling jets of the character shown in FIGS. 34 and 35, and applicable to any desired embodiment of the present invention.

FIG. 46 is a diagrammatic representation viewed in plan of an actuating system for the directional and propulsion controllers of the embodiment of the invention shown in FIG. 34.

FIG. 47 is a diagrammatic vertical cross section along line 47-47 of FIG. 46.

FIG. 48 is a diagrammatic view in plan similar to FIG. 46, but disclosing an electrically powered actuator.

FIG. 49 is a top plan view showing blower and motor controllers substituted for the jet controllers of FIGS. 46, 47 and FIGQSO is a horizontal cross section of another embodiment of the present invention taken along the line 50-50 of FIG. 51.

FIG. 51 is a vertical cross section taken generallyalong line 51-51 of FIG. 50.

I FIG. 52 is a vertical cross section taken generally along line 52-52 of FIG. 50. FIG. 53 is a horizontal cross section taken generally along the line 53-53 of FIG. 51.

FIG. 54 is atop plan view of the embodiment of the present invention shown in FIGS. 50 to 53.

Various words implying direction and the like. such as "horizontaP, upper, lower. verticall are used herein for the sake of brevity. and it is to be understood that the devices described by such words may have other directions and positions.

Referring first to FIGS. 1-3, a structure 30' or lifting platform having a relatively rigid supporting member is supported slightly above the ground" surface 30 by an air cushion formed by a peripheral air space 38, a plenum chamber 36 and a core air space 34 during normal operation of the structure. Air moving means or superatmospheric pressure air supply means in the form ofa centrally located blower or fan 40 and a motor 42 are supported by the relatively rigid supporting member, including an upper horizontal panel 44 and an enclosing side wall or peripheral orbital or circular support 46 which forms the plenum chamber 36 of the air cushion. The motor 42 and fan 40 are supported by wires or springs 48 from the members 74 in any suitable manner. The air blowing means 40 has an air intake means or collar 50 with an inward flange 51, and the blower is connected with the surrounding atmosphere 52 and discharges air from said surrounding atmosphere 52 at superatmospheric pressure into said plenum chamber 36 which is part of said air cushion. This maintains the air of the air cushion in air spaces 34, 36, and 38 at superatmospheric pressure.

A flexible, hollow, columnar diaphragm curtain 54 may be an orbital, flexible, channel shaped, sheet curtain which may be of any suitable horizontal cross section, which, in this em bodiment, is orbital or circular. The curtain 54 is sealed to, and is suspended from, the peripheral side wall 46 of the sup porting member 44, 46, and surrounds at least the lower part or core space portion 34 of said air cushion spaces 34, 36 and 38. The curtain 54 has its lower edge 56 slightly spaced at 58 from said ground surface 30, during normal operation for restrained escape of air, as indicated by arrow 60 from said air cushion air spaces 34, 36 and 38 between said lower edge 56 and said ground surface 30.

The curtain 54 may be a double-walled orbital, channel shaped sheet curtain which has an outer wall 62, which may be substantially circular in horizontal cross section in this embodiment and an upper edge which is secured and suspended at 64 from the side wall or orbital support 46 and extends to the lower edge 56, which is the intermediate low periphery of the curtain.

The outer wall 62 has a sidewise extension, bend, member 66 by which the inner wall 68 is joined to the outer wall 62. The inner wall 68 slants inwardly and upwardly from the lower edge 56 of the curtain 54 to an inner upper edge 70 which is suspended on a support or ring 71 inside the vertical bounds of said peripheral support 46 and within the upper part of the air cushion air space 34 and is spaced from the horizontal panel or platform 44 so the air of the main spaces 34, 36 of the air cushion flows freely in and out of the space 38 between the inner wall 68 and the outer wall 62.

The curtain 54 of this embodiment, and the curtains of the other embodiments herein disclosed, are relatively very thin in comparison to their other dimensions. They preferably are made of thin, flexible, air-impermeable, relatively nonstretchable material, such as a plastic material with or without reinforcing threads or other reinforcing strands molded in it.

For example, for the curtain 54 of this embodiment of the size specified, the material may be made of polyethelene film I and the like of i2 mils (.012 inch) thickness. Other sizes and embodiments may have curtains with the same or proportionally varied dimensions of thickness.

Generally, the film for this and other embodiments. is so thin, compared to its width or length, that it may be relatively non-self-supporting in an edgewise direction.

The material for all of the embodiments may be flexible plastic, such as polyethelene or Mylar, thin rubber, or the like, with nylon or other strong threads or other reinforcing strands molded in it to render it relatively nonstretchable.

The curtains of all of the embodiments are subjected to a relatively low pressure differential between the inner superatmospheric pressure in the air cushion and the atmospheric pressure of the surrounding atmosphere. Such pressure differential between the air in the cushion and the air in the surrounding atmosphere may be as low as in the order of a fraction of an ounce per square inch, or more.

The material for the curtain of any of the embodiments may be cloth made substantially impervious by treatment such as by plastic impregnation and the like. It may be similar to impregnated cloth now sold for kitchen tablecloths, and the like, of a sufficiently flexible type capable of hanging of its own weight as a straight cylindraceous or cylindrical curtain.

The air cushion formed by air spaces 34, 36, 38 is substantially free of unyielding obstructions a substantial distance above the lower edge 56 of the curtain 54 so the structure may pass freely over relatively high objects, such as large stones 72, and the like, as shown in FIG. 10. The slant of the inner wall 68 permits the stone 72 or high object to pass outwardly from the curtain 54 as well as inwardly, as the craft passes over the stone. 1

The ring 71 is secured to two horizontal cross members 74 which are supported on the side wall 46, by way of example. The relative height of the curtain may be varied, depending on the clearance height desired.

A plurality of skids 76 may be secured to the ring 71 and may extend to the upper panel 44, if desired, as indicated at 77. These skids support the rigid structure slightly above the ground" surface 30 when it is not in normal operation in substantially the same manner as in FIG. 24. The skids all extend in parallel direction with the inverted arches 76A extending parallel to the forward motion of the car.

If desired, a seat 78 may be placed on top of the panel or platform 44. Such seat may be supported on upright bars or columns 80, which may be secured to the collar 50, and horizontal bars 82 extending radially inward from the bars 80.

A suitable size for this embodiment is 8 feet in diameter at the side wall 46. The side wall 46 may be l8 inches in vertical extent. The curtain 54 may be 26 inches from the lower edge 56 to the upper edge 64.

In general, the height of the curtain 54 may be 20 percent- 30 percent of the diameter of the side wall 46 and the spacing of the upper edges 64 and 70 has operated successfully when it is approximately 10 percent more or less of such diameter.

The above dimensions are given by way of example only and not by way of limitation of the broad principles of this invention.

When the structure of FIGS. 1-3 is not operating, it rests on the ground surface 30 on the skids 76. If the operator desires to ride, he sits on the seat 78 and closes a switch, not shown, which energizes the motor (if electric) through the medium of a long electric cord which is connected to a source of power and to the motor. This causes the blower or fan 40 to rotate. A gasoline engine, self cranking if desired, may be used in lieu of the motor, and may also be started by a cranking switch.

Air from the surrounding atmosphere 52 is withdrawn through inlet defined by the collar 50 and is discharged by the blower 40 into the air cushion spaces 34, 36, 38 at superatmospheric pressure. The structure then quickly rises from the 

